The hyphen is a form of punctuation most often used to join words that have a combined meaning and/or indicate a break in a word at the end of a line of text. However, they have a variety of other uses:
- Creating compound words, particularly modifiers before nouns (the well-known actor, my six-year-old daughter, the out-of-date curriculum)
- Writing numbers twenty-one to ninety-nine and fractions (five-eighths, one-fourth)
- Adding certain prefixes to words: When a prefix comes before a capitalized word or the prefix is capitalized, use a hyphen (non-English, A-frame, I-formation). The prefixes self-, all-, and ex– nearly always require a hyphen (ex-husband, all-inclusive, self-control), and when the prefix ends with the same letter that begins the word, you will often use a hyphen (anti-intellectual, de-emphasize), but not always (unnatural, coordinate, cooperate). Use a good dictionary when in doubt. For further information about compound nouns and compound modifiers, see the separate section on compound words.
When you use a hyphen, remember that there is no space between a hyphen and the character on either side of it.